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CVE-2026-90091

Bluetooth: L2CAP: fix race l2cap_sock_cleanup_listen() vs. put_chan PUBLISHED

Description (CNA)

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: L2CAP: fix race l2cap_sock_cleanup_listen() vs. put_chan For L2CAP sockets without owning sk->sk_socket, reading l2cap_pi(sk)->chan may race against concurrent l2cap_sock_kill() -> l2cap_sock_put_chan(). This excludes simultaneous proto_ops callbacks, but access in l2cap_sock_cleanup_listen() has unsafe lockless read. [Task 1] [Task 2 (hdev->workqueue)] l2cap_sock_release(parent) l2cap_disconn_cfm l2cap_sock_cleanup_listen l2cap_conn_del bt_accept_dequeue l2cap_chan_del lock_sock(sk) l2cap_sock_teardown_cb bt_accept_unlink bt_sk(sk)->parent = NULL release_sock(sk) ----------------> lock_sock(sk) parent = /* NULL */ lock_sock(sk) <--------------------- release_sock(sk) sock_set_flag(sk, SOCK_ZAPPED) l2cap_sock_close_cb l2cap_sock_kill(sk) l2cap_sock_put_chan chan = READ l2cap_pi(sk)->chan l2cap_pi(sk)->chan = NULL l2cap_chan_hold_unless_zero l2cap_put_chan(chan) kref_get_unless_zero(&chan->ref) Task 1 may observe NULL which causes null-ptr-deref. Fix the race by taking lock_sock() in l2cap_sock_kill() to synchronize with l2cap_sock_cleanup_listen(). hold_unless_zero() is not needed here, l2cap_pi(sk)->chan owns reference if it is non-NULL. Clarify code comments vs. locking.

Affected (CNA)

Vendor / productVersions
Linux / Linuxaffected b39298044e5534612511a2ff5de03ba5f6e7a820 before 827de6bd2865b22aaabd554540def3b8a33018ab; affected 8c37e4338c801ebb8cee52436c01c41e009f6e87 before 7c7ac736b50fa259ed1bdddc18d79523f07c0442; affected 84e718b6a814edc84159361f9f454a4e92ae91ae before 4f8c63fe0097c9f6ea34409f82f79b3894903d91; affected 36da806f7fbaee56ad9e81859deec203f9728700 before 61d5ddbd524c715b224cbe7e9f01da4e05098b19; affected 6fef032af0092ed5ccb767239a9ac1bc38c08a40 before 32a7bc6e93be36b37fe61f351d312d358195bd61; affected 6fef032af0092ed5ccb767239a9ac1bc38c08a40 before 66d6ef18548ae6d7dd452b84115fc82c0a73a4ea; affected 733e76e74e406c1d1ddc7369420dd8a47f48bb8a; affected 6.1.178 before 6.1.188; affected 6.6.145 before 6.6.157; affected 6.12.97 before 6.12.110; affected 6.18.40 before 6.18.52; affected 7.1.5 before 7.2
Linux / Linuxaffected 7.2; unaffected 0 before 7.2; unaffected 6.1.188 through 6.1.*; unaffected 6.6.157 through 6.6.*; unaffected 6.12.110 through 6.12.*; unaffected 6.18.52 through 6.18.*; unaffected 7.2.6 through 7.2.*; unaffected 7.3 through *

CWE

No CWE identifiers supplied.

References